Mycobacterium abscessus outbreak: Organism originated in tap water prompting use of filters

An intensive three-month investigation has prompted Greenville Health System to install what may be the state’s first bacteriologic point-of-use water filters in a hospital operating room setting in the wake of a surgical infection that affected 15 patients. Other measures include eliminating slow-flow areas of internal water pipes, flushing scrub sinks for 10 minutes in the morning before first use and strengthening a machine’s manufacturer-recommended disinfectant schedule. The preliminary findings issued Monday could not identify one specific process or piece of equipment that triggered the outbreak. Officials said the Mycobacterium abscessus organism apparently originated in the water.

This light photomicrograph revealed some of the histopathologic cytoarchitectural characteristics seen in a mycobacterial skin infection./CDC

Mycobacterium abscessus is normally found in soil and water around the United States and does not cause infections in normal healthy individuals. The bacterium, while a common environmental contaminant, is a rare cause of a surgical site infection.

“We now believe that surgery processes involving the use of tap water may have inadvertently brought the organism into the perioperative environment,” said Robert Mobley Jr., M.D., GHS’ medical director of quality. “Although we use sterile water in or near the surgical sterile field, even something as seemingly safe as pre-surgery hand washing may have contributed. At this time, we have not been able to find any single cause or process as the trigger for the outbreak, but we’ve taken extraordinary measures to protect our patients – and believe we’ve succeeded. With patient safety as our first priority, we are taking protective measures to prevent further exposure to tap water in the operative environment.”

The Centers for Disease Control and Prevention (CDC) said that these investigations are complicated and similar investigations elsewhere have not identified a specific source of the infections. GHS, in conjunction with the S.C. Department of Health and Environmental Control (DHEC) and CDC, conducted the investigation.

No additional infections have occurred to date. A fourth patient has now died, with hospital officials saying it’s possible that the infection may have been a contributing factor. Only two other patients remain hospitalized. Hospital officials said all affected patients had serious underlying medical conditions but could not discuss specifics because of patient privacy laws.

There are no national standards of care about whether hospitals should screen for this bacterium or how they should treat tap water inside the facility. The bacterium is harmless in most circumstances but can result in infections if it comes into contact with surgical sites, especially in immunocompromised individuals. Exposure pathways of potential concern also include inhalation and entry of organisms through abraded skin, according to the Environmental Protection Agency.

CDC said the organism is in most tap water. Water studies showed that some water samples inside Greenville Memorial Hospital tested positive for the bacterium. EPA regulations do not require that it be eradicated because the organism is not thought to be harmful to the general public under normal circumstances. The environmental bacteria are considered widespread and part of the natural flora of potable water in the U.S.

This is the first time GHS has experienced an outbreak of surgical site infections involving mycobacterium.

For specifics on the findings, please see GHS’ update on the investigation and recommendations from DHEC detailing its findings and recommendations.

“We acknowledge the need to provide our patients with information, but an in-depth analysis requires adequate time,” said Mobley. “It would have been inappropriate to speculate while in the very early stages of the investigation. Our focus was – and always will be – on protecting our patients and providing them answers as we knew the facts.”

Because of the organism’s long incubation period of an average of 79 days in the GHS patients, patients did not typically show signs of infection until as long as several months after their surgeries. At that point, it then took as much as two additional months to grow and identify the bacterium through laboratory testing, and then several more months to complete DNA molecular typing needed for final identification of the type of specific genus.

“The overwhelming majority of surgical patients treated at Greenville Memorial have not been affected by this rare mycobacterial infection, and we apologize for any concern that we may have caused among our patients or in the broader community,” said Mobley. “The infection has been associated with only a few specific types of invasive surgery. But we believe in transparency and thought it was important to notify the community about the infection out of extreme precaution to ensure their safety and to alert them about possible symptoms.”

Although the investigation had not yet provided conclusions, it was decided, out of an abundance of caution, that GHS would notify patients who were believed to be at risk for developing this infection based on the investigation at that time. A letter was written to make these patients aware of the situation and to ask them to notify their surgeon should they develop signs of infection. Letters were sent, via regular and certified mail, to approximately 180 patients on whom specific cardiopulmonary surgical equipment had been used.

“We are proud of the work we do at Greenville Health System. As tough as this has been, our expertise and programs as an academic health center allowed us to see this developing problem and quickly deal with it,” said Mobley. “Our expertise is exceptional, and we’re grateful to the extraordinary team who identified and tirelessly worked to institute stronger protection.”

GHS has one of the strongest infection prevention and detection programs in the state. Likewise, GHS’ hand-hygiene rate and program is a national success story. National Healthcare Safety Network (NHSN) reports that the GHS cardiac artery bypass graft infection rate for 2013 was 33% lower than the expected rate for similar patients nationwide.

“This was an atypical situation, and we want to share our findings and research with other hospitals and healthcare providers in the state in the hopes that it will provide a forum for discussion,” said Mobley. “If more stringent guidelines – or, at least a clearer understanding of the problem – can come out of this situation, then it will be good for our patients as well as the entire healthcare industry.”

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